1,2,3,6-Tetrahydropyridine → tert-Butyl 4-(5,6-dihydropyridin-1(2H)-yl)piperidine-1-carboxylate

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Reaction Steps

4-Oxo-piperidine-1-carboxylic acid tert-butyl ester (797 mg, 4 mmol), 1,2,3,6-tetrahydropyridine (349 mg, 4.2 mmol), sodium cyanoborohydride (126 mg, 2 mmol), zinc chloride (410 mg, 3.2 mmol), and anhydrous methanol (20 mL) were mixed together and the mixture stirred overnight at room temperature. The solvent was evaporated from the mixture and the residue partitioned between 1 N sodium hydroxide and dichloromethane. The phases were separated and the aqueous layer extracted with dichloromethane. The organic extracts were combined, dried over magnesium sulfate, and the solvent evaporated. The residue was purified by flash column chromatography (1:1 hexanes/ethyl acetate to ethyl acetate to 1:3 methanol/ethyl acetate) to give 800 mg (75%) as a colorless oil. 1H-NMR (CDCl3, 400 MHz) δ 5.75-5.70 (m, 1H), 5.68-5.64 (m, 1H), 4.13-4.07 (m, 2H), 3.08 (m, 2H), 2.71-2.60 (m, 4H), 2.48-2.41 (m, 1H), 2.15 (m, 2H), 1.82-1.79 (m, 2H), 1.49-1.38 (m, 11H).

Provenance & Evidence